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실내모형시험을 통한 사질토 지반에서 군말뚝과 터널의 수직 이격거리에 따른 하중분포 및 지반거동 분석
오동욱,이용주,Oh, Dong-Wook,Lee, Yong-Joo 한국터널지하공간학회 2017 한국터널지하공간학회논문집 Vol.19 No.3
도심지에서의 터널굴착은 상부구조물과의 상호거동에 대한 이해가 필수적이다. 도심지에 사용중인 대부분의 구조물은 말뚝기초로 상부의 하중을 지지하고 있어, 터널 굴착 시 반드시 영향을 받는다. 따라서 본 연구에서는 실내모형시험을 통해 기존의 군말뚝 기초 하부 터널굴착에 따른 축력 분포와 지반의 거동을 분석하였다. 말뚝 기초는 2, 3 열 말뚝으로 가정되었으며, 말뚝 선단부와 터널 천단부의 이격거리는 터널직경에 대한 일반화를 위해 터널 직경(D) 대비 0.5D, 1.0D 그리고 1.5D로 고려되었다. 지반은 약 30%의 상대밀도(Dr)를 가지는 느슨한 사질토로 형성되었으며, 말뚝의 축력 분포를 측정하기 위해 말뚝에 변형률게이지(strain gauge)를 부착하였다. 또한, 이격거리에 따른 군말뚝의 침하와 인접지반의 침하를 변위센서(linear variable differential transformer; LVDT)와 다이얼게이지(dial gauge)를 통해 측정였으며, 터널굴착에 따른 지중의 변형을 근거리사진계측기법(close range photogrammetric technique)을 통해 측정하였다. 수치 해석을 통해 실내모형시험 및 근거리사진계측 결과와 비교 분석하였다. 본 연구에서는 체적손실율(volume loss; $V_L$) 개념을 이용하여 터널굴착을 모사하였으며, 1.5%로 적용되었다. 연구결과, 이격거리가 멀어질수록 말뚝의 축력감소는 작게 나타났으며, 침하량은 모두 유사한 경향을 나타내었다. 특히, 말뚝 선단부와 터널 천단부의 이격거리가 0.5D에서 1.0D로 증가할 때 축력과 침하량의 가장 큰 감소율이 가장 큰 것으로 나타났다. Tunnelling in urban areas, it is essential to understand existing structure-tunnel interactive behavior. Serviced structures in the city are supported by pile foundation, since they are certainly effected due to tunnelling. In this research, thus, pile load distribution and ground behavior due to tunnelling below grouped pile were investigated using laboratory model test. Grouped pile foundations were considered as 2, 3 row pile and offsets (between pile tip and tunnel crown: 0.5D, 1.0D and 1.5D for generalization to tunnel diameter, D means tunnel diameter). Soil in the tank for laboratory model test was formed by loose sand (relative density: Dr = 30%) and strain gauges were attached to the pile inner shaft to estimate distribution of axial force. Also, settlements of grouped pile and adjacent ground surface depending on the offsets were measured by LVDT and dial gauge, respectively. Tunnelling-induced deformation of underground was measured by close range photogrammetric technique. Numerical analysis was conducted to analyze and compare with results from laboratory model test and close range photogrammetry. For expression of tunnel excavation, the concept of volume loss was applied in this study, it was 1.5%. As a result from this study, far offset, the smaller reduction of pile axial load and was appeared trend of settlement was similar among them. Particulary, ratio of pile load and settlement reduction were larger when the offset is from 0.5D to 1.0D than from 1.0D to 1.5D.
수직 벤투리관 내부 유동 가시화 및 고속 차압 측정에 관한 실험적 연구
오동욱(Dong-Wook Oh),배재현(Jae Hyun Bae),박장민(Jang Min Park),이정호(Jungho Lee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Vertical Venturi tube is widely utilized in flow rate and gas volume fraction (GVF) measurement of 2-phase flow. Fast traveling gaseous slugs act as source of pressure fluctuation and distract the differential pressure reading of the Venturi tube. In this paper, flow dynamics of travelling air slug inside a transparent Venturi tube is analyzed through high speed flow visualization system coupled with differential pressure sensor. This investigation is believed to result in better understanding of the flow rate and gas volume fraction measurement of two-phase flow which is frequently encountered in multiphase flow for flow assurance on offshore oil and gas plant.
지속가능한 보존관리를 위한 지역 근대문화자원 아카이브 구축 연구
오동욱(Oh, Dong-Wook) 한국지역사회학회 2018 지역사회연구 Vol.26 No.1
The purpose of this study is to suggest a direction for building archives of modern cultural resources which are scattered around the inner city of Daegu. The inner city of Daegu is an important region with a lot of historical and cultural resources an potentials as a living city museum. However, there is no system to manage and utilize modern cultural resources. Therefore, it is necessary to build a Modern Cultural Resource Archive to strengthen cultural power of the inner city of Daegu. The Modern Cultural Resource Archive refers a hub center for preserving, managing and utilizing modern cultural resources. In this study, the archival subjects were classified into six subjects; 1) historical person related to culture, arts and national movement, 2) religious groups, 3) educational organizations, 4) public facilities, 5) living facilities, and 6) modern alleys. In this study, a plan for utilizing archives of modern cultural resources was also suggested, which would help to increase the policy effectiveness related to archives.
층상구조를 가진 증발식 열교환기 습채널의 표면 젖음도 해석
오동욱(Dong-Wook Oh),박재범(Jae Bum Park),송찬호(Chan Ho Song) 대한설비공학회 2016 설비공학 논문집 Vol.28 No.7
One of the most important factors for determining the thermal performance of an evaporative cooling system is the wettability of the evaporative heat exchanger surface. Evaporation of a widely spread water film on the heat exchanger surface promotes heat transfer between the “dry” air and “wet” air passages. Hydrophilic coating is generally applied on the heat exchanger surfaces to increase the wettability of the heat exchanger surface and the COP of the evaporative cooling system. In this paper, a simple lamellar patterned structure is suggested to maximize the spreading of a water film on the vertically oriented walls. The capillary height of the lamellar structured grooves is analyzed through a theoretical model, and the results are compared with the numerical analysis through a finite element analysis tool, SE-FIT. A good agreement between the theoretical model and the numerical analysis can be observed as long as the channel depth is comparable to or larger than the channel width of the lamellar structure.
오동욱(Dong-Wook Oh),남기언(Ki Ean Nam),송찬호(Chan Ho Song),윤석호(Seok Ho Yoon),이공훈(Kong Hoon Lee),김욱중(Ook Joong Kim) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
In this paper, heat transfer and pressure drop characteristic of plate-fin heat exchangers for evaporative cooling system is investigated. Thermal performance and pressure drop of heat exchangers with different louver fin pitches are compared. Experiments are conducted for heat exchangers with different louver fins at the average air flow velocity of 3 m/s . 5.5 m/s. The thermal performance data are analyzed by using the effectiveness-NTU method. Pressure drop and overall heat transfer coefficient are measured as a constant temperature condition is given to the heat exchanger unit.